Sir Mike Penning, who served under Mrs May at the Home Office, and ran her leadership campaign in 2016, accused her of trying to ‘blackmail’ MPs into supporting it.

In a statement to the Hemel Gazette, he said: “She is playing a game of Russian Roulette with the country which is frankly an insult to the referendum result and all those people who voted, no matter how they voted.

“To say to the likes of myself ‘It’s Chequers or a hard Brexit’. It’s like making us sit on the naughty step at school. She’s driving MPs like me to the European Research Group, because they are the only ones actually representing Conservative MPs and their constituents.”

Speaking to the Gazette afterwards, he added: “Quite simply, she needs to wake up and smell the coffee. I’ve kept quiet about my concerns for a long time, but I cannot just sit out and let this disaster unfold.

“The PM needs to realise that the Chequers deal is unacceptable to me and the vast majority of the country. Constituents are writing to me on a daily basis saying they cannot support a deal which leaves us beholden to the EU.

“A large number of moderate MPs feel the same way. The PM needs to realise that the numbers just don’t stack up and unless Labour support it, Chequers cannot get through Parliament.

“She has a golden opportunity now, to change things for the better. Because the EU will make a deal at the last minute - that’s how they’ve always operated.

“I urge the Prime Minister to use what we’re saying as a weapon, a negotiating weapon, with the rest of the European Union to get a deal much better than Chequers, because if she comes back with Chequers it is as dead as a dodo.”